Other Comprehensive Income and Accumulated Other Comprehensive Income (details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Accumulated other comprehensive income [Roll Forward]
Accumulated other comprehensive income, net of tax, balance, beginning of year			$ 810	$ 2,236
Other comprehensive income before reclassifications			480
Amounts reclassified from accumulated other comprehensive income			10
Other comprehensive income (loss), net of taxes	(262)	(15)	490	(1,531)
Accumulated other comprehensive income, net of tax, balance, end of period	1,300	705	1,300	705
Changes in net unrealized gains on investment securities having no credit losses recognized in the consolidated statement of income	(154)	(204)	901	(2,370)
Changes in net unrealized gains on investment securities having credit losses recognized in the consolidated statement of income	1	(2)	4	2
Net changes in benefit plan assets and obligations	15	24	45	78
Net changes in unrealized foreign currency translation	(203)	112	(149)	(57)
Other comprehensive income (loss) before income taxes	(341)	(70)	801	(2,347)
Income tax expense (benefit), other comprehensive income (loss)	(79)	(55)	311	(816)
Changes in Net Unrealized Gains on Investment Securities Having No Credit Losses Recognized in the Consolidated Statement of Income [Member]
Accumulated other comprehensive income [Roll Forward]
Accumulated other comprehensive income, net of tax, balance, beginning of year			1,125
Other comprehensive income before reclassifications			610
Amounts reclassified from accumulated other comprehensive income			(20)
Other comprehensive income (loss), net of taxes	(99)	(132)	590	(1,546)
Accumulated other comprehensive income, net of tax, balance, end of period	1,715		1,715
Changes in net unrealized gains on investment securities having no credit losses recognized in the consolidated statement of income	(154)	(204)	901	(2,370)
Income tax expense (benefit), other comprehensive income (loss)	(55)	(72)	311	(824)
Changes in Net Unrealized Gains on Investment Securities Having Credit Losses Recognized in the Consolidated Statement of Income [Member]
Accumulated other comprehensive income [Roll Forward]
Accumulated other comprehensive income, net of tax, balance, beginning of year			197
Amounts reclassified from accumulated other comprehensive income			2
Other comprehensive income (loss), net of taxes		(1)	2	2
Accumulated other comprehensive income, net of tax, balance, end of period	199		199
Changes in net unrealized gains on investment securities having credit losses recognized in the consolidated statement of income	1	(2)	4	2
Income tax expense (benefit), other comprehensive income (loss)	1	(1)	2
Net Benefit Plan Assets and Obligations Recognized in Shareholders' Equity [Member]
Accumulated other comprehensive income [Roll Forward]
Accumulated other comprehensive income, net of tax, balance, beginning of year			(431)
Amounts reclassified from accumulated other comprehensive income			28
Other comprehensive income (loss), net of taxes	10	15	28	50
Accumulated other comprehensive income, net of tax, balance, end of period	(403)		(403)
Net changes in benefit plan assets and obligations	15	24	45	78
Income tax expense (benefit), other comprehensive income (loss)	5	9	17	28
Net Unrealized Foreign Currency Translation [Member]
Accumulated other comprehensive income [Roll Forward]
Accumulated other comprehensive income, net of tax, balance, beginning of year			(81)
Other comprehensive income before reclassifications			(130)
Other comprehensive income (loss), net of taxes	(173)	103	(130)	(37)
Accumulated other comprehensive income, net of tax, balance, end of period	(211)		(211)
Net changes in unrealized foreign currency translation	(203)	112	(149)	(57)
Income tax expense (benefit), other comprehensive income (loss)	$ (30)	$ 9	$ (19)	$ (20)